Cranes are typically used to lift and/or relocate loads from one location to another. Generally, cranes are used to lift or lower loads between a ground level or from a transport vehicle to a different elevation. In other applications, cranes are used to relocate loads from one location, such as a cargo carrier to a land vehicle. In all applications of the use of cranes, a load is generally lifted by a hook mechanism suspended by a cable at the end of a boom. The boom can be lifted vertically and rotated from side to side to move the load to a variety of horizontal and vertical locations.
The operation of a crane requires a high degree of skill so that the loads can be moved efficiently and safely. The safe operation of a crane is especially important when mounted to a mobile vehicle, such as a truck. In this situation, if the load is heavy and extended horizontally too far from the truck, the crane will overbalance the vehicle and cause it to tip over. This occurrence can not only lead to damage of the load, but also nearby structures, as well as the vehicle and the operator and persons in the vicinity of the crane operation.
The skill in the operation of a crane is apparent. The operator must be knowledgeable of the various loads that can be lifted as a function of the angle of the boom with respect to a horizontal reference, or the radius of the load. This is complicated with the operation of cranes that have the ability to shorten and lengthen the boom. As the boom is lengthened, for a given load radius, the load capacity is less. The operators of cranes are provided with readily available graphs and other information so that the safe operating parameters are not exceeded.
Cranes are conventionally equipped with various sensors and switches to control the safe operation of the crane. The switches are connected to hard wired control apparatus so that when an overload is sensed, the control apparatus disables further operation of the crane. For example, cranes equipped with load sensors provide disable signals when a load exceeding the rated limit is encountered. In these rudimentary control systems, there are no visual readouts of the exact nature of the problem, only the apparent problem that the crane will not operate. The skill of the operator is required to not only be aware of the activation of any of the control switches, but also to quickly diagnose all indications of imminent problems and remedy the same before a catastrophe occurs.
The diagnosis of problems with the normal operation of a crane has been automated to provide the operator with a visual readout of a code representative of the problem. Kar-Tech of Delafield, Wis. markets a Versa Remote full featured remote control system for a use with cranes. This system is processor-controlled and connected to various sense switches of the crane to provide a self diagnosis when various parameters of the crane have been exceeded. Once diagnosed, the controller provides a read-out code so that the operator can be made aware of the nature of the problem. A wireless transmitter is also marketed by Kar-Tech to provide coded signals to the controller to activate and deactivate the various components of the crane, such as boom rotation, extension, up/down movement of the boom, and a hoist for winding and unwinding the wire rope cable.
There remain yet other areas for controlling cranes and similar equipment to increase the safety of the operators and the equipment itself. For example, the operator is yet able to cause the crane components to be moved at speeds that may be unsafe, as a function of the load. This discretion is still vested with the operator. Accordingly, there are yet various areas where this control can be monitored and overridden if the conditions dictate that the operator is operating the crane near or outside the envelope of safe operation.
It can be seen from the foregoing that a need exists for a diagnostic system for automatically diagnosing an imminent problem concerning the speed of operation of the crane components, and providing the operator of an indication thereof. Another need exists for a control system which overrides the operator commands to move the crane at a rate that is unsafe to personnel or equipment, as a function of the load conditions. Yet another need exists for a system that includes a controller for controlling the various movements and actions of a crane in response to wireless commands, a number of sensors coupled to the controller, and a software program in the controller for responding to the sensor signals for diagnosing problems and generating an error code for presentation on the display. A further need exists for a technique for downloading new or revised diagnostic software programs into the controller.